Bows have been used for many years as a weapon for hunting and target shooting. More advanced bows include cams that increase the mechanical advantage associated with the draw of the bowstring. The cams are configured to yield a decrease in draw force near full draw.
For optimal bow performance, substantial synchronization of rotation of the cams is required, but often problematic to achieve in practice. Synchronization typically requires secondary strings and pulleys that control the rotation of the cams, such as disclosed in U.S. Pat. No. 7,305,979 (Yehle). These additional features increase the weight, cost and maintenance of such devices, while adding additional friction, further decreasing the potential speed of the projectile.